Geologic Timeline Reflection

The first major event in Earth's history was the cyanobacteria oxygenating the atmosphere. This radically changed the composition of Earth's atmosphere and is the reason most current life exists. There was a mass extinction event that killed off the obligate anaerobes. This probably caused life on land to appear. This also allowed stimulated evolution to survive in oxygen rich environments. The next most event in Earth's history was the Permian extinction event. This was the deadliest mass extinction event in Earth's history killing 90% of marine organisms and 70% of terrestrial organisms. It is speculated that it was caused by an eruption or release of gas from the ocean. It ended the paleozoic era and made way for the mesozoic era. It took 30 million years for life recover and there is a gap in the fossil record because of the event. The last major event was the Cretaceous mass extinction. It was the last mass extinction and well known for ending the dinosaurs and mesozoic era. A giant meteorite crashed onto Earth's surface killing three quarters of all life on Earth. It is very important because it ended the dinosaurs and let mammals take over which would eventually give rise to humans. The scale of Earth's history is impressive and makes you realize how insignificant you are in a grander scale. I was surprised that  the Precambrian lasted so long and that we have a lot of blanks for information on the Precambrian. The Precambrian stretched most of the room while the rest could fit on a table. Many scientists say we are in the middle of the 6th mass extinction event because our killing of species through deforestation is killing many species. Many mass extinctions take thousands of years and if we don't change, we could be the cause of a mass extinction that will probably lead to the end of humans. I want to know more about the early Precambrian and how life formed because it seems strange how such complicated life could come from random assortment of chemicals. click here for picture

Unit 8 Reflection

Unit 8 was about the constant change of species. We started this unit learning about artificial selection, the process in which humans choose the best traits from the gene pool of a species, and purposely mate them with others with the same traits to produce individuals with the best traits for their tasks. This is used livestock by creating the hugest turkey or cattle so that it can produce the most meat and food. The next vodcast was about Charles Darwin's discoveries and theory of evolution. He traveled to the Galapagos islands and recorded four major observations. The first was that sexually reproducing species tend to have higher genetic variation. The second observation was that traits are inherited from parent to offspring. The third observation was that all species are capable of growing exponentially, beyond their carrying capacity. The last observation was that competition is stiff and not all offspring survive because of limited food and other resources. He concluded that individuals who inherited traits that help them survive better and reproduce more tend to leave more offspring than other individuals. The second conclusion was that the unequal ability of individuals to survive and reproduce will result in the better traits becoming more common in the population over generations. He came up with the idea of natural selection, the process of weeding out traits in a population that don't help individuals survive leaving trait that are neutral or do help survive. We next learned of the gene pool, the collection of all alleles in a population. Allele frequency is the frequency of an allele in the gene pool when compared to the other alleles. Speciation in when one species becomes two new species. This means neither can reproduce with the other one. This is caused by behavioral, geographical, and temporal isolation. We then learned of the structural evidence that evolution has occurred such as vestigial structures, remnants from our ancestors that we inherited and do not use anymore, as well as other techniques scientists use in trying to find evidence for evolution. We then learned of three ways populations tend change in allele frequency: directional selection, stabilizing selection, and disruptive selection. We also learned of genetic drift and other ways evolution occurs. We finally learned of the history of life according to evolution. We of the eras and periods the history of life is divided into and theories in how life started.
I want to learn more about the Precambrian era because I still have a lot of information I want to know about it. It is the largest era in terms of time and is when life emerged which is vitally important if we want to understand how life came to be, yet we know the least about this era. This unit has been successful in completing my beginning of the year goals because I have been more on time with my assignments and doing the CFU's more regularly. I need to work on being assertive and haven't worked on it because I haven't seen many opportunities where it is essential to be assertive. I will try to be more assertive in the next unit. You can look at my Unit 7 Reflection here.